Glycosaminoglycans are a polysaccharides family formed by the repetition of an uronic acid, a glucuronic or iduronic acid, 1→4 or β 1→3 linked to a hexosamine, glucosamine or galactosamine residue. The hexosamine and hyaluronic acid residues can be sulfated in various ways. In glycosaminoglycan family, in addition to heparin sulfate and heparan sulfate, hyaluronic acid and chondroitin sulfate are also included. Physiologically, glycosaminoglycans are organized in proteoglycans, formed by a protein nucleus to which glycosaminoglycan is linked by means of a connecting region. These structures have a control role in biochemical reactions by means of the captation and release of proteins and growth factors (J. F. Kennedy, C. A. White, Bioactive Carbohydrates, 1983, Ellis Horwood Ltd, 211-227).
In particular, chondroitin sulfate is localized in cartilages and epithelial portion of the gastric mucosa or in the urothelium. It confers the characteristic of elasticity to cartilages and controls the resistance thereof, whereas in mucosa and epithelium it protects the epithelium itself from the acid attack in the case of gastric epithelium and from potassium in the case of urothelium. In diseases where the amount of chondroitin sulfate is low, such as e.g. in gastritis or interstitial cystitis, the administration of chondroitin sulfate helps in alleviating the inflammation and related damages due to the low chondroitin sulfate content.
Chondroitin sulfate is formed by the disaccharide repetition containing β 1→3 glucuronic acid linked to galactosamine which is sulfated or in position 4 or in position 6. In the same molecule both ChSA and ChSC groups are present. Occasionally, small amounts of disulfated and non-sulfated disaccharides can also be present in the polysaccharide chain.
Hyaluronic acid is a non-sulfated glycosaminoglycan formed by a disaccharide linear sequence of 1-3-glucuronic acid linked to a N-acetylglucosamine.
Hyaluronic acid is ubiquitous in epithelial and connective tissues, e.g., but not only, in skin and cartilages.
The use of combinations of chondroitin sulfate and hyaluronic acid in the regeneration of damaged joint cartilages, e.g. due to osteoarthritis, is known.
Also the intradermal use of hyaluronic acid and/or chondroitin sulfate as a filler of soft tissues and mucosae, e.g. as a “filler” in the aesthetic medical treatments, is known.
The above treatments are effective but present the drawback that they need to be repeated very frequently, since the injected components are quickly reabsorbed by the recipient organism.